Nearly 200 countries are working to finalise an agreement in December to radically curb the use of fossil fuels. Developing as well as industrialised nations have submitted contributions to a deal.

China has announced its carbon dioxide emissions will peak by 2030 and has offered US$3 billion in finance to help poorer countries green their economies.

But while China appears to accept previous UN regimes where only developed countries take action on climate are no longer viable, Kerry indicated he was getting different vibes from Narendra Modi’s government.

“India has been more cautious, a little more restrained in its embrace of this new paradigm, and it’s a challenge,” he said.

Kerry added that India’s move to expand domestic coal use were “not in the direction we ought to be moving in,” adding, “we have to be careful not to be holier-than-thou or accusatory”.

Kerry insisted there could be no return to legally binding agreements like the 1997 Kyoto Protocol, where only countries deemed developed in 1992 were mandated to take action.

“We have to break the old mentality… this is not 1992, this is not 1997, this is not the same Kyoto kind of breakdown,” he said.

In a shot across the bows of the EU and other blocs hoping for a new legally binding deal in Paris, Kerry said there was “definitively not going to be a treaty,” which would likely require Senate approval.

Brussels is pushing hard for a treaty or protocol, but privately officials say they will accept a legal agreement that ensures all countries must take steps to tackle emissions.

Speaking to media on Thursday, France foreign minister Laurent Fabius stressed any deal in Paris would still contain binding elements regardless of what it was called.

“Jurists will discuss the legal nature of an accord on whether it should be termed as a treaty or an international agreement,” Fabius told reporters.

“But the fact that a certain number of dispositions should have a practical effect and be legally binding is obvious so let’s not confuse things, which is perhaps what Mr Kerry has done.”

On the thorny issue of finance, Kerry also offered hope the US could soon deliver some of the $3 billion pledged to the UN’s flagship green fund.

Republicans in Congress have successfully blocked contributions to what one Senator recently described as a “slush fund”, but Kerry said he was confident the White House would win over.

“We’ll get there, because the trade-offs of the budget are such that when something is a high enough priority for a president, you have a way of getting it done, even though it’s opposed by people,” he said.

“If the president is prepared to veto the budget because it hasn’t included it, you can usually find some money.”